Of interest to the process specialist, engineer, scientist, and others, is the quality or purity of product (media capable of particle suspension) being manufactured whether it liquid, gas, pharmaceutical, or the like. One measure of product quality is an assay of particulate matter or concentration of particulate matter within the end product or product during various stages of production so as to assure that particulate matter as a constituent of, or by product of the process, exists at a prescribed amount or within a suitable tolerance. When the particles in suspension are unknown, the particles may differ in composition, size, and shape. It is well known that matter interacts with light in a variety of ways, as example by means of absorption, reflection or scatter, and fluorescence to name a few. Various optical means have been devised to measure particulate matter within a suspension such as turbidimeter or nephelometer, particle counter, and densitometer but all use fundamentally different optical configurations each designed to measure a specific attribute or concentration range of the suspended particles by means of transmittance, reflection, or remittance of light.
Another constraint on the optical measurement configuration is imposed by regulatory agencies or by standardized methods by example the U.S. EPA Method 180.1, ASTM Standard Test Method for Turbidity of Water D 1889-00, and by International Standard ISO 7027 for the determination of turbidity for the assay of water quality. These methods and standards dictate the geometrical relationship of emitter to detector and the solid angle of collection optics so as to assure that instrument of similar task perform within designated parameters for reporting purposes.
Other limitations on devices for nephelometric measurement designed to determine the presence of particles in a suspension is the ability of the device to operate over a wide range of particle sizes and concentrations without impediment. Particle counters perform well at low concentration of particles but are prone to obstruction when the concentration or particle size becomes greater than the ability of the flow steam to pass through the narrow restriction, orifice, or capillary of the measurement interrupter. Devices, such as a turbidimeter, with unrestricted flow paths are insensitive to small concentrations of particles because the primary measurement technique relies on scattered light energy impinging on the detector means is greater than that of the self-generated noise of the detector.
Still another deficiency of devices used in the measure of particles in suspension is a lack of means to evaluate the operational readiness of the instrument without disruption of particle flow by the introduction of a calibration standard or calibration device, requiring interaction between a skilled operator or technician and the nephelometric device.
The disclosed invention eliminates the need for multiple nephelometric measuring devices and also system verification devices in order to perform assay of the presents or absence or number of suspended particles in a media as well as verification of the systems ability to measure in compliance to required performance attributes.